TAXONOMY OF TROMBICULIDS 
141 
genu may be barbed; galeal seta nearly always branched or ciliated (but ?nude in myzantha); bases of 
chelicers typically angulated laterally (regularly in akamushi- group) ; no long outstanding nude or plumose 
setae on legs; larvae parasitic on mammals and secondarily to a limited extent on birds. Nymphs & 
Adults without eyes ; precoxal plates to coxae I present ( Palways) and fused to form a longitudinally 
divided sternum. Womersley also describes a rectangular epistome with the anterior margin slightly 
concave or sinuous, finely denticulate; tarsi I are tapering, widest proximally. 
Remarks . — This subgenus is usually taken to be synonymous with the akamushi- group. 
Womersley has restricted the larval diagnosis thus, but has accepted a number of species which 
fall outside it on larval characters but are included on nymphal characters. The present writer 
believes that there are good reasons for broadening this subgenus to include such species. 
The nearest relations appear to be the subgenera Trombiculindus and Trombicula , and certain 
unallocated species such as T. jayewickremei Worn., the nymph of which has no precoxal 
plates. 
The angulation of the cheliceral bases was recorded as a character of the akamushi - group 
by Wharton (1946:173). It is occasionally present in unrelated chiggers, e.g. in some 
Euschongastia , and may not always be present in species now included in the broad subgenus. 
The diagnosis of the akamushi - group usually includes the specific palpal formula 
N/N/BNN. Species such as T. palpalis with palpal formula N/N/BNB are thus excluded. 
The writer has a specimen (species near deliensis) from Imphal with the plapal tarsus BNN 
on one side and BNB on the other. It is probable that too much insistence is placed on this 
feature, and that palpalis and related species should reasonably be placed in the akamushi- 
group. On the other hand, there is considerable variation in the scutal shape, one group 
showing a tendency for the PL setae to creep up the sides of the scutum away from its rounded 
posterolateral corners, so that the sensillary bases come to he well behind the fine of the PLs, 
as in pallida. This “ pallida - subgroup ” also shows a tendency to unusual development of 
the scutal (especially PL) and dorsal setae, with more or less thickening and development of 
heavy barbs (compare the blade-like processes of T. baluensis Traub & Audy, this Study 
p. 48). The members of the subgenus Trombiculindus (see below) have the same palpal 
formula (N/N/BNN) and scutal shape but the setal modification has gone much further: it is 
possible that there may be a close link here. With these considerations in view, we may 
attempt a tentative regrouping of the subgenus as shown in the following tabulation. 
There is an indeterminate group comprising jayewickremei , muscae , philipi , quadriense , 
and taphozous , all of which appear to be related. All but jayewickremei are bat-chiggers. 
The nymph of jayewickremei has been described by Womersley under his subgenus 
Neotrombicula, without the fused precoxal plates. These species have the sensillary bases 
relatively close together considering the width of the scutum (cf. gliricolens, which Dr. Raja 
Varma has bred to the nymph and, in a personal communication, has placed in Leptotrombidium). 
They may be related either to Leptotrombidium or to Trombicula , probably the former. 
* Old World species . — Europe & U.S.S.R. : Imuscae, russica , orientalis, pavlovskyi, subakamushi. Africa: 
le-gaci, natalensis. Asia & Pacific: akamushi NA, baluensis T. & A., bhimtalensis , bodensis N, burmensis 
N, burnsi, deliensis NA, dux, fuji , fulleri N, gliricolens, himizu, intermedia, keukenschrijveri N, kitasatoi, 
kuroshio, lanceolata, longiseta N, macacus, micula T & A N, miyairii, miyajimai, miyazakii, murotoensis, 
myzantha N, pallida A, palpalis, parapalpalis, pelta, pilata T. & A., pipellae T. & A., puta, robusta, 
scutellaris, sylvestris N, tarsala T. & A., tenjin, teramurai, tithwalensis, tosa, villosa , yasuokai; tanaka- 
ryoi, muridia, ?muscae-group , kawamurai; 11 n. spp. to be described. 
New World species. — mexicana, myotis, panamensis, potosina. 
Subgenus Trombiculindus Radford 1948 
Type. — Trombiculindus squamosus Radford 1948:126, Proc. Zool. Soc., Lond. 118, 213-272. From 
a rat, Himalayan range, India. — ( continued on p. 143) 
*In this and all following lists, the letters N, A following a name show that that species has been 
bred to the Nymph, Adult, to the writer’s knowledge. Those with authors shown “ T & A” are new 
species described by Traub & Audy, 1953, in this Study — See pp. 45-88. 
MALAYA, No. 26 , 1953 
